The Mars Science Laboratory rover, named Curiosity, made a successful landing on the surface of the red planet, drawing shouts and cheers from the mission control staff at NASA's Jet Propulsion Laboratory. University of Redlands professor Tyler Nordgren explains what Curiosity may discover.

TOM GJELTEN, HOST:

This is TALK OF THE NATION. I'm Tom Gjelten.

But first, we're going to go to our final story today and that is on the Curiosity rover mission. Eight and a half months after it was launched from Cape Canaveral, Florida, NASA's Curiosity rover last night reached its destination, Mars. The mission control team at the Jet Propulsion Laboratory in Pasadena, California, nervously followed the seven-minute entry and descent process and then the landing.

(SOUNDBITE OF BROADCAST)

UNIDENTIFIED MAN: UHF is good. (unintelligible) confirmed. Received on line.

(SOUNDBITE OF CHEERING)

UNIDENTIFIED MAN: Time to see where our Curiosity will take us.

(SOUNDBITE OF CHEERING)

GJELTEN: And with that, the $2.5 billion Curiosity project was underway. Moments later, Curiosity beamed back its first images of the Martian surface. Over the next two years, the rover will be exploring. It'll look for signs of water on Mars, as well as other evidence to indicate whether the Martian environment could support life.

Tyler Nordgren is a professor of physics and astronomy at the University of Redlands. He's part of the team of scientists who designed an instrument that the Curiosity rover is carrying that'll insure that Mars will be seen in its true colors in the photos it sends back to Earth, and he joins us in a moment.

If you have questions about the Curiosity mission, give us a call at 1-800-989-8255. Our email address is talk@npr.org, and you can join the conversation at our website. Go to npr.org, and click on TALK OF THE NATION. And Tyler Nordgren joins us now from Redlands, California. Welcome to you, sir.

TYLER NORDGREN: Oh, thank you. A pleasure to be here.

GJELTEN: So what makes this landing historic?

NORDGREN: It's the most complicated landing to ever take place on another planet. Absolutely stunning, and it's - for the first time, we have a landing system that's so precise that we could afford to take this expensive rover and go some place spectacular with it. We just landed right next to a three-mile tall mountain.

GJELTEN: And explain how can that landing process work? You're landing next to a mountain. How were you able to guide that craft down to that particular landing spot and land it successfully?

NORDGREN: Well, the folks at Pasadena, at the Jet Propulsion Laboratory who do entry, descent and landing, EDL, they're - they are professionals at this point. The engineers there, they had targeted Curiosity. They knew exactly where to point it. And it is the equivalent of you've hit a hole-in-one from the other side of the Earth. So because of the time delay in getting a signal back from Mars, all of this had to be completely done autonomously by the spacecraft itself. Nobody here on Earth could control it once it hit that atmosphere.

GJELTEN: So we heard that raucous cheering from the control room there when it became clear that the landing was successful. Was that the most worrisome part of this whole mission? Are there going to be many other moments - suspenseful moments as you watch from Earth what's happening there on Mars?

NORDGREN: Mars is not forgiving. I think back to Spirit, the Spirit rover that landed in January of 2004. That was the rover that had the airbags that landed. It rolled, it bounced. And when it finally opened up, we had this wonderful, perfectly working rover on Mars. But about a week into the mission, something went wrong. Turned out there was a glitch with how the software interacted with memory. And so for about two weeks, we had lost contact with the rover on Mars, and there was a worry that the mission might have ended at that point. But the folks at JPL, they were able to get it working again and Spirit operated for another several years.

GJELTEN: And how does this rover compare to Spirit, the earlier rover? Have you improved the technology? I imagine you have.

NORDGREN: This is - it's amazing what just leaps and bounds in technology have gone along and every mission that NASA has sent to Mars. The very first rover that NASA sent back in 1997 was Sojourner, just a little thing, about the size of a toaster. And then Spirit and Opportunity came along in 2004 about the size of a golf cart. But they were mobile geologists and, in fact, Opportunity is still working on the surface of Mars eight years later.

So, now, we've got Curiosity. Curiosity, about the size of a Mini Cooper. This thing should have - it's projected to have a lifetime of two years - that's the nominal mission. But whereas Opportunity was supposed to last nominally for 90 days, it worked for eight years. Who knows how long Curiosity could go, so this is a mobile geology/chemistry laboratory and it's - who knows what's in store for it.

GJELTEN: Well, OK. You say it's a mobile geology/chemistry laboratory. And what kind of information have you programmed or will you be instructing the rover to send back to Earth?

NORDGREN: Every kind of life that we know here on Earth requires three things. It requires some kind of a solvent, liquid water in the case of here on Earth, sunlight or some form of energy and then organic molecules. And we know, at this point, that Mars has got at least two of those three. There is sunlight there. There's also volcanism or ancient volcanism and, thanks to Spirit and Opportunity, we know that there used to be liquid water flowing across the surface.

So the big thing is to now look for the signs of organic molecules, so Curiosity is going to drive around. It's going to be able to dig into the soil, drill in the rocks, fire a laser at rock faces and look for the vaporized elements that come off and really look to see if the building blocks of life are actually present there in the landing spot.

GJELTEN: And how big is that? Well, you say landing spot. How big is the territory that it will be able to explore? What's the distance it can travel and what do you know about that surface and what kind of hazards might be there?

NORDGREN: Well, right now, it looks like, from the initial hazard camera images that are aimed at the wheels, that we are on a hard, flat surface with little uniform pebbles everywhere. So, at the moment, I can't think of a better place for that rover to go driving. In the distance, we see some sand dunes and, beyond that, I'm looking at one of the images coming out from the forward camera, the forward hazard camera, and there is a three mile tall mountain directly in front.

So this rover is going to be able to drive for maybe - I think the last I saw - about 30 meters per day, potentially, so at least for the near term, we're going to stay in one spot and look to just be very, very careful about what do we see around us? We're at the edge of a big alluvial fan and what that means is that water is potentially drawn material out of the nearby crater rim and brought it down to about where we're landing.

So, by looking at the surface around us, we could potentially sample what was up there in that crater rim. So there's great science to be done without moving anywhere at the moment.

GJELTEN: Now, from Spirit, of course, and Opportunity, we saw color pictures from Mars, but I now understand that those color pictures weren't necessarily accurate in terms of the true colors that were presented. You were part of a team of scientists that developed a sundial that'll help calibrate the color of the Martian landscape images so that, in fact, Mars can be seen in its true colors. How did you do that?

NORDGREN: Well, there's a calibration target and the idea is, if you think back to days of film when you would take a photograph of a landscape here on earth and you would take your film into the color lab to make prints, the lab technician would look for things like trees, green grass, blue sky, ways to make sure that the color calibration had been done correctly. Of course, we don't have any of those things on Mars, so we needed to send something along that had known regions of particular colors and gray and black and white so that we could actually effectively calibrate out the true images, the true colors on Mars because think about this. Mars has got this atmosphere with dust all through it, so right now, we're on a surface where you've got sunlight filtering through this red dust. So if you want to know what kinds of rocks you're looking at - well, you can't just tell from the color because, right now, everything has got this red shade draped over it.

So we've sent this calibration target, which has a post in the middle so that we can see what these colors look like in direct sun and in shadow. Well, that's what a sundial is, so in fact, the fellow who first thought of turning this into a working sundial was Bill Nye, the Science Guy. And he thought, let's take an opportunity for this little dry technical instrument and turn it into a means of outreach to the public.

GJELTEN: Tyler Nordgren is professor of physics and astronomy at the University of Redlands and he's answering our questions about the Curiosity rover that landed on the surface of Mars today.

Let's go now to Vince, who's on the phone from Houston, Texas. Good afternoon, Vince. Thanks for the call.

VINCE: Yeah. One of the burning questions I've had for years - when I was in high school, I studied Voyager quite a bit. On the mission to Mars, how do they navigate around potential asteroids in the asteroid belt?

NORDGREN: A great question. I recall asking that myself when I was in school. It turns out that every image that you've probably ever gotten of an asteroid belt like, say, from "Empire Strikes Back," is false. The asteroid belt is actually a huge region and so, even though there are lots of asteroids out there, they turn out to be very, very far between, so in particular, the Galileo spacecraft, which was sent out to Jupiter to go into orbit around Jupiter - NASA had to specifically target it in order to get it anywhere near an asteroid.

And it photographed the first two asteroids that flew through the asteroid belt, so it's actually very hard to get close to something in space. Space, by and large, is empty.

GJELTEN: You're listening to TALK OF THE NATION from NPR News. And let's go now to George, who's on the line from San Jose, California. George, welcome to TALK OF THE NATION. You're on the air.

GEORGE: Good afternoon. Congratulations on your most recent success. I have a question, though, about the software problems you've had in the past. You mentioned this Spirit opportunity memory management problem, which almost prevented those rovers from moving off their pad. Also, there was a Mars orbiter, I believe, that crashed into the planet because the software team didn't use the correct units. They used feet instead of meters, I think.

NORDGREN: Yeah.

GEORGE: So what has NASA learned from these past mistakes and incorporated into the software process?

GJELTEN: Dr. Nordgren?

NORDGREN: Well, one of the things NASA's learned - and I will freely admit that I have not been expert on the software in terms of entry and descent and landing - but one of the things that NASA's learned is to test everything. You can't make any assumptions. Whenever you assume, you wind up with a problem, so since the crash back in '99 because of that unit conversion problem, NASA has been very, very careful to test, retest.

When you have different teams building different parts and putting things together, you can't just test the individual parts. You need to also test them once they're assembled into a unit and so it's really that backup upon backup upon backup that has really allowed these last several missions to be successful.

But who knows what is hiding out there that we never imagined might be waiting for us? So I can not say that there are not going to be some nail biting moments left in the future, but we learn from our mistakes and we learn that you do not take anything for granted. Not on Mars.

GJELTEN: Well, of course - thank you George for that call. Of course, one of the big things that we're looking at in the future is the possibility of a manned mission to Mars and that will be many times more nerve-wracking.

Casey writes, with astronauts having spent several months at the International Space Station, is the Mars rover mission the next step towards sending people to Mars? Will Curiosity be collecting data that'll help scientists determine if traveling to Mars is possible?

NORDGREN: Yeah. That's the hope. NASA's entire Mars program has been built upon taking small steps, building upon the mission that's come before and, right now, the plan is that we would love to be able to send people to Mars. In fact, part of the reason why you had this hair (unintelligible) seven minutes of terror landing system that seemed like such a Reub Goldberg method compared to the airbags was that, if we were ever to send people to Mars, you can't put people into an airbag. You have to have a system like what we had tonight.

So this is just that first step in building the whole complicated network of equipment necessary to take people to Mars.

GJELTEN: Let's go now to Chip, who's on the phone from San Antonio, Texas. Chip, welcome to the TALK OF THE NATION. And, Chip, I'm having trouble getting you on the air.

So what is the next step now and what is NASA's funding picture look like? Will there be a new mission after this?

NORDGREN: You know, that's the sad thing and I say this with a heavy heart because, here, you have just seen perhaps the most spectacular thing that NASA engineers have ever done on Mars and, at the same time, NASA's budge for space exploration and Mars exploration is being cut and so NASA has just had to cancel plans for another mission.

And, when you think about it, every man, woman and child here in the U.S. - we pay something like half a cent in our taxes towards Mars, towards NASA. And your half a cent just got you a nuclear-powered all-terrain vehicle with a laser landing on Mars in the most dramatic fashion flawlessly. I think that's a half cent well spent.

GJELTEN: And how soon are we going to be seeing these dramatic pictures? It sounded like you're actually - are you watching a live feed? You know, are you able to see a live feed right from your office?

NORDGREN: I'm looking at the raw images that have just come down from the latest pass and...

GJELTEN: What do you see?

NORDGREN: ...I'm waiting, along with everyone else, for the next download of images. What's going to happen next is, eventually, they're going to raise the main mast camera on there and slowly check out all the systems, one-by-one. The first color image is going to come - not from the main panoramic camera on the mast, but actually from a color camera on the robotic arm and that camera is kind of a hand microscope, but it's a hand microscope that's able to focus at infinity. So we're actually going to be able to get a full color beautiful image from this little microscope.

GJELTEN: Pretty exciting. Tyler Nordgren is a professor of physics and astronomy at the University of Redlands. He joined us via phone from Redlands. Thank you so much, Dr. Nordgren.

Tomorrow, we'll look at the doctor and nurse shortage in the U.S. It may get worse before it gets better. Join us for that. This is TALK OF THE NATION from NPR News. I'm Tom Gjelten in Washington.

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